25 public questions tagged with this topic.
Taq polymerase is a thermostable DNA polymerase used in PCR to amplify DNA sequences.
Ref: NCERT Class 12 Biology Chapter 9: Biotechnology: Principles and Processes Polymerase Chain Reaction - PCR and Applications
DNA polymerase is used to synthesize new DNA strands by adding nucleotides to a growing DNA chain, making it essential for DNA replication and PCR.
Ref: NCERT Class 12 Biology Chapter 9: Biotechnology: Principles and Processes Polymerase Chain Reaction - PCR and Applications
DNA polymerase extends primers to synthesize new DNA strands during PCR.
Ref: NCERT Class 12 Biology Chapter 9: Biotechnology: Principles and Processes Polymerase Chain Reaction - PCR and Applications
Helicase unwinds the DNA double helix, allowing replication and transcription to occur.
Ref: NCERT Class 12 Biology Chapter 9: Biotechnology: Principles and Processes Tools - Restriction Enzymes - Molecular Scissors
DNA polymerase requires an RNA primer to initiate replication because it cannot start synthesis de novo.
Ref: NCERT Class 12 Biology Chapter 5: Molecular Basis of Inheritance Post-Transcriptional Modifications - Capping Splicing Polyadenylation
DNA polymerase I removes RNA primers and fills the gaps with DNA nucleotides during replication.
Ref: NCERT Class 12 Biology Chapter 5: Molecular Basis of Inheritance DNA Replication - Semiconservative and Machinery
DNA polymerase does not unwind the DNA helix; helicase is responsible for this function.
Ref: NCERT Class 12 Biology Chapter 5: Molecular Basis of Inheritance DNA Replication - Semiconservative and Machinery
DNA polymerase III synthesizes the lagging strand in short Okazaki fragments during DNA replication.
Ref: NCERT Class 12 Biology Chapter 5: Molecular Basis of Inheritance DNA Replication - Semiconservative and Machinery
DNA polymerase catalyzes the addition of nucleotides to the growing DNA strand during replication.
Ref: NCERT Class 12 Biology Chapter 5: Molecular Basis of Inheritance DNA Replication - Semiconservative and Machinery
DNA polymerase does not unwind the DNA helix; helicase is responsible for this function.
Ref: NCERT Class 12 Biology Chapter 5: Molecular Basis of Inheritance DNA Structure Double Helix and Packaging - Nucleosome
Bacterial RNA polymerase elongates roughly 40-50 nucleotides per second, significantly slower than DNA polymerase III synthesizing DNA near 750-1000 nucleotides per second during replication. Reduced rate attributed to lower processivity because transcription includes frequent pausing, backtracking for proofreading via GreA/GreB, waiting for regulatory factors like NusA, and requirement to unwind DNA continuously. Replication utilizes sliding clamp beta conferring high processivity and topoisomerases cooperating efficiently. Transcriptional pausing facilitates coupling with translation, co-transcriptional folding, attenuation, and regulatory checkpoints absent in highly processive replication optimized for rapid genome duplication.
Ref: Berg Biochemistry Chapter 28: Transcription rate slower than replication processivity; Watson Chapter 13 Elongation speed comparison
RNA polymerase active site geometry allows de novo initiation without oligonucleotide primer. Structural studies reveal holoenzyme accommodates initiating NTPs at positions +1 and +2 base-paired to template DNA within catalytic cleft, stabilized by Watson-Crick interactions and base stacking with sigma factor contacts. Formation of first phosphodiester bond does not require pre-existing 3' hydroxyl unlike DNA polymerases. Consequently polymerase can start RNA chains at any promoter-defined site. This fundamental difference between replicative and transcriptional enzymes enables transcription to initiate spontaneously at regulatory signals without primase activity, simplifying gene expression control.
Ref: Watson et al. Chapter 13: RNA polymerase de novo initiation mechanism no primer required; Alberts Chapter 6 Active site NTP stabilization
